Obturator trap for rocket propellants



Nov. 8, 1949 c. N. HICKMAN 2,487,053

OBTURATOR TRAP FOR ROCKET PROPELLANTS Filed Nov. 16, 1,944

26 in 0W Blar ante Nfi ckman Patented Nov. 8, 1949 OBT'URATOR TRAP FOB ROCKET PROPELLANTS Clarence N. Hickman, Jackson Heights, Y., assignor to the United States of America as represented by the Secretary of War Application November 16, 1944, Serial No. 563,740

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 4 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to rockets and more particularly to rockets for propelling a high explosive grenade, and particularly to a new and improved combined trap and obturator.

One form of rocket motor useful for propelling a high explosive grenade consists essentially of a cylindrical tubing made from steel or other metal having suflicient mechanical strength to withstand the pressure of the combustion products liberated by the propellent material adapted to be contained within the cylindrical tubing. One end of the tube is fitted with an ogive type of head adapted to contain the high explosive material. This head is hollow and is secured to the tube by means of a sleeve which is adapted to contain the percussion fuze for detonating the high explosive on impact of the head with the target. This slee e has a base portion which provides a partition forming a seal for the gases liberated by the propellant preventing such gases from gaining access into the percussion iuze and high explosive contained in the head. The opposite end of the tube has secured thereto a Venturilike nozzle for the discharge at a high velocity of the combustion products liberated by the propellant.

Firings with these rocket grenades from a shoulder gun projector have on occasion been accompanied with prematures. By premature" is meant the detonation of the high explosive contained within the head prior to impact of the head with the target or other object. Obviously, these prematures are undesirable, particularly if they occur within the vicinity of the firing personnel. It has been determined that the metal which forms a partition between the chamber of the propellant and the container for the high explosive was occasionally characterized by the presence of blow holes and such blow holes" might at least account for some of the prematures" by permitting the hot propellant gases within the combustion chamber to gain entrance into the iuze retained in the sleeve and into the high explosive of the head.

Accordingly, it is an object of this invention to provide a rocket projectile construction wherein an obturator is arranged between the combustion chamber and the explosive head of the rocket.

A particular object of this invention is to provide an improved rocket projectile construction wherein a single member functions both as an 2 obturator and as a trap for the propellent material.

In accordance with this invention an obturator member is provided in the combustion chamber of the rocket projectile to prevent leakage of propellent fluid into the high explosive containing portion of the projectile. Inasmuch as forward suspension of propellent material has been found to be particularly desirable, a rocket construction in accordance with this invention utilizes a single member located in the forward end of the combustion chamber which serves both as an obturator with respect to the propellent gases and as a support or trap for the outer sticks constituting the propellent charge.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawing in which:

Fig. 1 comprises an elevational view of a longitudinal section of a preferred embodiment of an obturator and trap combination.

Fig. 2 is an elevational view in longitudinal section of a modification of the structure shown in Fi 1.

3 is a cross-sectional view taken on the plane 3-3 of Fig. 1.

Fig. 4 is a cross-sectional view taken on the plane 4-4 of Fig. 1.

Fig. 5 is a cross-sectional view taken on the plane 5-5 of Fig. 1.

Referring now to the drawing and particularly to Fig. 1, the high explosive and armorpiercing head I of the rocket has secured thereto a cylindrical sleeve 2, which is provided with reduced diameter solid portion 3 externally threaded for engagement with a cylindrical housing 5 forming the rocket motor combustion chamber. An inertia type firing pin 6 is supported .within the sleeve 2, restrained from movement longitudinally therein by an arming wire I, which is inserted through aligned openings formed in the sleeve 2 and the body of the firing pin 6. This arming wire is withdrawn at the time the propellant is loaded within the launching tube. A shear pin I0 is also inserted through aligned openings in the sleeve and the body of the firing pin 6, and is formed of soft metal adapted to be sheared upon impact of the head with the target to permit the firing pin to move longitudinally within thesleeve into engagement with a percussion primer 9.

The motor housing 5 has the walls at the end opposite the high explosive head swaged inwardly slightly to form a flared entrance to the throat it of the nozzle member H which is threadably secured to housing 5. A plurality of spaced fins 50 are secured to the periphery of nozzle member H. A gasket 20 is positioned in forward end of the combustion chamber between the solid portion 3 of the sleeve 2 and an obturator disc 2|. This disc has a cylindrical stud 23 welded thereto on the side oppositethe gasket 20. This stud has a plurality of pins 24 which extend radially therefrom to form a suspension support for a plurality of cylindrical powder grains 25. Each powder grain 25 is supported by having a pin 24 inserted thru a transverse opening 26 drilled in the ends of-the propellent grains in the manner shown in my copending application, Serial No. 551,047, filed August 24, 1944.

, Upon ignition, which is preferably from an igniter cup (not shown) supported within the nozzle flare, the gases liberated by the burning propellant press the disc 2| tightly against the gasket 20 thereby efiectively sealing the space behind the disc from the combustion products. The pressure of the combustion products acting on the base of the disc not only retains the disc 2| and propellant grains 25 in the forward part of the combustion chamber but also seals the partition formed by the base 3 of the sleeve 2 from these propellant gases, thereby preventing gases from gaining access into the head portion of the projectile, notwithstanding the presence of blow holes in the material forming the sleeve.

In the modification illustrated in Fig. 2 a construction is provided which is designed to avoid the necessity for using the gasket 20 of Fig. 1. In this modification the obturating clement comprises a disc 30 formed into the shape of a spherical surface segment and has a cylindrical stud 23 welded to its convex side. This stud has a plurality of radial pins 24, extending therefrom for supporting the propellant grains 25 longitudinally within the combustion chamber, in

the same manner as described for Fig. 1' by inserting the pins 24 thru openings 26 drilled diametrically thru an end of the propellant grains. Upon ignition the propellent gases, acting against the convex surface of the spherical shaped disc 30, force the sides of this disc into intimate engagement with the inner cylindrical surface of the housing to effectively seal the solid sleeve portion 3 behind this disc from the combustion products. In this manner the disc retains the propellent grains forwardly within the combus tion chamber during burning of the propellent material by virtue of the pressure differential existing on the opposite sides of this disc.

I claim:

1. In combination a rocket motor having a rearwardly open combustion chamber, a high explosive head secured to said chamber, partition means separating said high explosive head from said chamber, a propellant for said rocket motor comprising a plurality of elongated grains of propellent material, a trap supporting said grains longitudinally of the combustion chamber from the forward end thereof, and means responsive to the pressure of the combustion products liberated by said propellant for sealin said partition and holding said trap forwardly within said chamber.

2. The combination defined in claim 1 wherein said last named means includes an obturator disc having the trap for supporting said grains secured thereto.

3. In combination, rocket having a high explosive compartment and an adjacent propulsion chamber, said propulsion chamber containing a propellent material combustible to liberate a propellent fluid under pressure, a spherical segmental disc positioned within said chamber with the concave surface thereof facing said high explosive compartment, a trap rod secured to the convex surface of said disc whereby upon the application of the propulsion chamber pressure to the convex surface of said disc, the concave side of said disc engages the side walls of said propulsion chamber to seal the explosive compartment and retain the trap rod forwardly within the propulsion chamber.

4. In combination, a rocket motorhaving a combustion chamber, a high explosive head secured to said chamber, partition means separating said high explosive head from said chamber, a gasket member in said combustion chamber lying adjacent said partition means, a disc-like member arranged in said combustion chamber to forcibly compress said gasket member by pressure developed in said chamber, and a trap member secured to the side of said disc-like member facing said combustion chamber, said trap member constructed and arranged to secure a plurality of powder elements within said chamber.

CLARENCE N. HICKMAN.

REFERENCES. CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 483,126 Bates Sept. 27, 1892 2,145,507 Denoix Jan. 31, 1939 FOREIGN PATENTS Number Country Date 5,099 Great Britain Dec. 12, 1878 14,000 Great Britain May 29, 1897 

